We provide biostatistics expertise for a number of NIEHS and NTP researchers, as well as researchers at universities and other government agencies. In these collaborations, we provide advice about study design, analyze data, interpret statistical results, and participate in writing papers for publication. Over the past year, we have been involved in the four research areas described below. We have an ongoing collaboration with an intramural laboratory that is studying genetic changes and pathways related to fibroids, a common tumor in women. We assisted with the design, statistical analysis and interpretation of studies that investigated gene expression, particularly in response to estrogen, in human and monkey uterine tissue. Thus far, our findings suggest that estrogen interacts with the receptor tyrosine kinase pathway to regulate cell proliferation. As part of an NTP interagency agreement, we collaborated with researchers at NIOSH and the University of Cincinnati on a case-control study of the effects of genes and exposure to diisocyanates on the occurrence of occupational asthma. Based on our statistical analyses, we identified several cytokine and antioxidant defense gene polymorphisms that are associated with occupational asthma. The polymorphism having the strongest association is within the superoxide dismutase (SOD2) gene. We collaborated with several NIEHS researchers who focus on mechanisms of DNA repair, mutation, tumorigenesis and receptor activation. By testing for differences between genotype groups and/or calculating mutation probabilities, we found genes and sequences of events involved in DNA repair and activation of the glucocorticoid receptor and we identified mutation hotspots. Occasionally, mice and rats in NIEHS studies may undergo surgery and the pain associated with surgery needs to be minimized. Several veterinary analgesics are available to alleviate pain from surgery, but there is little information regarding their effectiveness in rodents. We assisted with the design of several studies in mice and rats, then analyzed data from these studies to compare candidate analgesics for pain relief. The results of these studies provided guidance to the NIEHS animal facility veterinarians regarding the analgesics that would be most effective.